root@beaglebone:/sys/devices/ocp.2/pwm_test_P8_13.9# pwd
/sys/devices/ocp.2/pwm_test_P8_13.9
root@beaglebone:/sys/devices/ocp.2/pwm_test_P8_13.9# ls
driver  duty  modalias  period  polarity  power  run  subsystem  uevent